s1_generate_a_series_of_files(){
    for i in {1..100};do
        filename="/tmp/new_file${i}"
        echo -n "${i}" > "${filename}"
    done
}

s2_list_4_files_in_long_format_about_account_and_group(){
    ls -l /etc/{passwd,shadow,group,gshadow} | sort
}

s3_find_items_related_to_given_username(){
    grep "^$1:" /etc/passwd /etc/shadow | sort
}

s4_find_items_related_to_given_username(){
    grep "^$1:" /etc/group/ /etc/gshadow | sort
}

s5_create_groups_for_given_group_names(){
    groupadd rnd
    groupadd itoperation
}

s6_create_users_and_set_their_group_as_required(){
    useradd -G rnd Adam
    useradd -G rnd Bod
    useradd -G itoperation Calvin
    useradd -G itoperation David
    useradd -G rnd,itoperation, Edward
    for username in Adam Bob Calvin David Edward;do
        username -l "${username,,}" "${username}"
    done
}

s7_change_users_shell(){
    chsh -s /usr/bin/sh adam
    chsh -s /usr/bin/sh edward
}

s8_set_password_change_policy(){
    for username in adam bob calvin david edward;do
        chage -m 10 -M 60 -W 10 "${username}"
    done
}

s9_set_password_change_policy(){
    echo "adam:${1}" | chpasswd
    echo "bob:${2}" | chpasswd
    echo "calvin:${3}" | chpasswd
    echo "david:${4}" | chpasswd
    echo "edward:${5}" | chpasswd
}

s10_lock_bobs_password(){
    passwd -l bob
}

s11_include_adam_into_wheel_group(){
    usermod -aG wheel adam
}

s12_change_files_permission(){
    for i in {3..99..3};do
        filename="/tmp/new_file${i}"
        chmod 640 "${filename}"
    done
}
